Proposals for driving military track vehicles by an electrical transmission commonly suggest the use of a single generator that powers two electric motors--one motor being operatively connected to the track on one side of the vehicle and the other motor being operatively connected to the track on the other side of the vehicle. The two motors are independently controlled, such that the vehicle moves in a straight manner when the speeds of the motors are equal, and the vehicle is steered when the speeds of the two motors are independently varied. During a turn in either direction, one track becomes the inner track (relative to the turn), and the other track becomes the outer track. A major drawback of this arrangement is the requirement that the vehicle be capable of delivering full torque to either of its two tracks. This requires that each motor be capable of operating under full output of the generator. However, during most maneuvers of the vehicle, half the generator output is delivered to each track so that each motor is operated at only half its rated capacity.
A second drawback to the previously proposed electrical transmission system is even more apparent when one considers how the vehicle is steered. More particularly, a track vehicle is steered by slowing one track and increasing the speed of the other track. As the inner track is slowed, it absorbs a sufficient mount of power, usually far in excess of the power required for propulsion--i.e., the power required to keep the vehicle moving along its intended path. When the speed of the inner track is decreased, it is required that the power that would otherwise be absorbed be transferred to the outer track so as to avoid the inefficiency of dissipating this power in the form of heat. If the power were lost, the vehicle would slow down significantly each time a turn is made. In a pure electrical system (devoid of mechanical devices), the transfer or feedback of this otherwise lost power from one motor to another is usually accomplished by the means of an electrical feedback system. Such a feedback is commonly termed "regeneration" and unless the electric motors are further oversized (over and above the capacity of the generator), the motor capacity limits the amount of power that can be regenerated from one track to the other. Moreover, even further losses are suffered because the electrical feedback paths are inherently less efficient than the mechanical paths presently used in hydrokinetic transmissions.